Hitherto, a technique of using an aluminum wire in a part of a coil of a motor to decrease the weight of the motor has been examined. When the aluminum wire is used in a part of the coil of the motor, a copper wire needs to be joined to the aluminum wire and thus there is a concern about electric corrosion. In order to prevent the electric corrosion, as a method of joining the copper wire to the aluminum wire, there is proposed a method of bringing end faces of both conductors into contact with each other and joining both conductors at a normal temperature (a cold pressure welding method (hereinafter, referred to as cold pressure welding)). The cold pressure welding is a highly reliable method of connecting wires using metal bonding at both new metal faces (non-oxidized metal faces) that are exposed when the wires are pressed against each other.
For example, Patent Literature 1 discloses a technique in which “a first conductor 10 and a second conductor 20 are connected to each other via a relay conductor 30”; “the first conductor 10 and the relay conductor 30, which are formed of different kinds of metal, are metal-bonded to each other by pressure welding”; and “the second conductor 20 and the relay conductor 30 are connected to each other by deforming a swaging piece 35, therefore, even when the second conductor 20 includes a stranded wire that is easily buckled, the second conductor 20 and the relay conductor 30 can be reliably connected to each other”.